Synthesis of Lateral Macrobicyclic Compartmental Ligands: Structural, Magnetic, Electrochemical, and Catalytic Studies of Mono- and Binuclear Copper(II) Complexes
A series of putative mono- and binuclear copper(II) complexes, of general formulas [CuL](ClO4) and [Cu2L](ClO4)2, respectively, have been synthesized from lateral macrocyclic ligands that have different compartments, originated from their corresponding precursor compounds (PC-1, 3,4:9,10-dibenzo-1,1...
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Published in | Inorganic chemistry Vol. 42; no. 10; pp. 3308 - 3317 |
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Main Authors | , , , , , |
Format | Journal Article |
Language | English |
Published |
United States
American Chemical Society
19.05.2003
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Online Access | Get full text |
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Summary: | A series of putative mono- and binuclear copper(II) complexes, of general formulas [CuL](ClO4) and [Cu2L](ClO4)2, respectively, have been synthesized from lateral macrocyclic ligands that have different compartments, originated from their corresponding precursor compounds (PC-1, 3,4:9,10-dibenzo-1,12-[N,N‘-bis{(3-formyl-2-hydroxy-5-methyl)benzyl}diaza]-5,8-dioxacyclotetradecane; and PC-2, 3,4:9,10-dibenzo-1,12-[N,N‘-bis{(3-formyl-2-hydroxy-5-methyl)benzyl}diaza]-5,8-dioxacyclopentadecane). The precursor compound PC-1 crystallized in the triclinic system with space group P1̄. The mononuclear copper(II) complex [CuL1a](ClO4) is crystallized in the monoclinic system with space group P21/c. The binuclear copper(II) complex [Cu2L2c](ClO4)2 is crystallized in the triclinic system with space group P1̄; the two Cu ions have two different geometries. Electrochemical studies evidenced that one quasi-reversible reduction wave (E pc = −0.78 to −0.87 V) for mononuclear complexes and two quasi-reversible one-electron-transfer reduction waves (E 1 pc = −0.83 to −0.92 V, E 2 pc = −1.07 to −1.38 V) for binuclear complexes are obtained in the cathodic region. Room-temperature magnetic-moment studies convey the presence of antiferromagnetic coupling in binuclear complexes [μeff = (1.45−1.55)μB], which is also suggested from the broad ESR spectra with g = 2.10−2.11, whereas mononuclear complexes show hyperfine splitting in ESR spectra and they have magnetic-moment values that are similar to the spin-only value [μeff = (1.69−1.72)μB]. Variable-temperature magnetic susceptibility study of the complex shows that the observed −2J value for the binuclear complex [Cu2L1b](ClO4)2 is 214 cm-1. The observed initial rate-constant values of catechol oxidation, using complexes as catalysts, range from 4.89 × 10-3 to 5.32 × 10-2 min-1 and the values are found to be higher for binuclear complexes than for the corresponding mononuclear complexes. |
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Bibliography: | istex:8E72C36A1C59C5E653CA894DD65F0BD0405E9513 ark:/67375/TPS-24T7JMTB-K ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0020-1669 1520-510X |
DOI: | 10.1021/ic020633+ |